MYTH: Nitrous is Flammable
Basically nitrous oxide by itself is pretty innocuous – it really doesn't do anything. In the form of nitrous oxide it is not dangerous or flammable – it just serves as an oxidizer in a racing application. It doesn't become an oxidizer until it breaks down into its components – two parts nitrogen and one part oxygen. In a racing engine, under normal circumstances, when the N20 is heated to 572 degrees Fahrenheit, it breaks down and releases oxygen into the mixture, allowing extra fuel to be burned. It basically provides a highly concentrated oxygen source, and of course, the higher the concentration of oxygen the faster the fuel will burn.
Keep in mind, however, that while nitrous itself is not flammable, if there's a least hint of fuel in the intake, it will ignite, and the heat will cause the nitrous to break down and release a rush of oxygen to the fire, which causes an explosive flash. That's because it's a real lean fire – if it were a rich fire it would barely cough. Plenum intakes will almost always hold a trace of fuel after the car is shut down, and that's where the trouble can start. The nitrous itself, without fuel, is not flammable. All it does is add oxygen to the flame and make it burn better.
There are incidents of nitrous-injected engines spitting flames out the hood scoop from time to time, but in almost every case this is the result of carelessness and lack of proper procedures on the part of the racer and his crew. You'll see a lot of cars that don't have a shut off valve on their nitrous line, and they'll leave the nitrous on while they're towing the car to the staging lane. If they have a leaking solenoid and most of them leak to a certain extent, and the nitrous is on to the intake, as soon as they turn the power switch on they create a spark. With the ignitions we use in racing, as soon as the power is turned on a plug will fire at random. If it happens to fire the one in the cylinder where an intake is open, it will shoot a spark right up into the intake, and if the nitrous has been leaking, it will cause an explosion - all simply by turning the switch on.
Again, this is a totally avoidable situation, and in no way due to the use of nitrous itself.

MYTH: Nitrous Alone Make Horsepower
Injecting nitrous oxide itself does not make horsepower. The introduction of nitrous oxide allows more fuel to be burned at a quicker rate, increasing horsepower. So it is the extra fuel added with the nitrous that makes more horsepower.

MYTH: I Got a Bad Fill
You hear a lot of people say somebody gave them a bad fill and just pumped their cylinder full of air. This is not possible because if you fill a cylinder full of air its weight will not change significantly. If your bottle is not filled properly it will not be the correct weight. This misconception comes from people not monitoring bottle pressure when activating their system. If the cylinder is too cold the pressure will decrease, hindering performance. If the cylinder is overheated the entire liquid contents will flash into gas, drastically changing the mass flow of nitrous through your system. Most systems are rated for pressures ranging from 900-1050 psi, which with a correctly filled cylinder would be 90-100 degrees.
Installing a nitrous pressure gauge on your cylinder does not help you monitor how full your bottle is. The only way to correctly determine how full a cylinder is by weight. If you only have 2 lbs of nitrous left in your cylinder, you can heat the cylinder to obtain 1000 psi nitrous pressure. But in heating the bottle to obtain this pressure you have boiled off that 2 lbs of liquid nitrous into a gas and when the system is activated performance will be hindered drastically because nitrous systems are calibrated for liquid nitrous. That is why your cylinder has a siphon tube that runs to the bottom of the tank to pick up and deliver liquid nitrous to your system.

MYTH: The Nitrous Used in Drag Racing is the same as Dentists Use
When administered for pain relief, nitrous oxide is mixed with oxygen to prevent brain damage and unconsciousness. The nitrous oxide used by your dentist is the purest form available, however, and if it was available to the general public you could use it in your engine. The nitrous oxide that is available to the general public for performance enhancement has sulfur dioxide mixed with it to avoid substance abuse. There is no performance advantage to be gained by obtaining medical grade nitrous for your engine.

MYTH: Nitrous Can Damage Your Engine
Nitrous oxide itself can not damage your engine. However, improper tuning and misuse of a nitrous system can cause drastic parts failure as will any mistuned turbo system or supercharged system. If you lean out or detonate any of these combinations engine damage will occur. Most nitrous systems, if used as directed, will not cause damage to your engine. Most people purchasing a nitrous system are looking for an edge on their competition. Carelessly attempting to tweak more out of their combination then the equipment was designed for, however, as in any performance engine, can and ultimately will result in engine damage.
Nitrous systems are constant flow, this means that at any engine rpm you are injecting the same amount of nitrous and fuel. Most systems are not designed to be used under 3500 rpm, below this rpm the engine is spinning so slow that the cylinder is overfilled with nitrous and fuel causing combustion pressures that are too hard for most engines to sustain.
When disassembled, an engine with a correctly tuned nitrous system will have no signs of fatigue anymore so than an engine run just as hard with no nitrous. In many cases, boosting performance with nitrous oxide will prove to be more reliable and less maintenance dependant than using exotic camshaft profiles and high compression pistons.
That pretty well covers the category of nitrous oxide mythology, but there are some other important aspects regarding the proper use of N2O, and the Speedtech team wanted to be sure this information was made available to the racing community.